1. Field of the Invention
The invention relates to a motor vehicle and, in particular, to a motor vehicle that includes a motor for a front wheel that can input motive power to the front wheel and can receive motive power output from the front wheel, a motor for a rear wheel that can input motive power to the rear wheel and can receive motive power output from the rear wheel, and a battery that can transfer electric power to or receive electric power from the motor for the front wheel and the motor for the rear wheel.
2. Description of Related Art
In the past, as for such a motor vehicle, a following structure is put forward: the motor vehicle includes an engine; a first motor; a power distribution comprehensive mechanism (planetary gear mechanism) that has a ring gear, a carrier and a sun gear connected with a drive shaft connected to a front wheel, an output shaft of the engine and a rotating shaft of the first motor; a second motor that can input motive power to the drive shaft and receive motive power output from the drive shaft; a third motor that can input motive power to the rear wheel and receive motive power output from the rear wheel; and a battery that can transfer electric power to or receive electric power from the first motor, the second motor and the third motor (see Japanese Patent Application Publication No. 2006-248319 (JP 2006-248319 A), for example). In this motor vehicle, a rear wheel demand distribution ratio serving as a demand value of a ratio of a torque of the rear wheel to a sum of a torque of the front wheel and the torque of the rear wheel is set in accordance with whether or not a slip occurs, whether or not it is a time of a start and emergency acceleration, or whether or not it is a time of a travel at a decelerated speed, the torque for the front wheel and the torque for the rear wheel are set based on the set rear wheel demand distribution ratio, and the engine, the first motor, the second motor and the third motor are controlled so as to output the set torque for the front wheel to the front wheel and output the set torque for the rear wheel to the rear wheel. Thereafter, the rear wheel demand distribution ratio is specifically set so as to suppress the slip during the occurrence of the slip, set to, for example, 0.2 or 0.3, so as to make a starting performance and an accelerating performance become good during the start and emergency acceleration, set to, for example, 0.5 or 0.4, so as make electric power obtained through a regenerative drive of a motor MG2 and a motor MG3 become more during the travel at the decelerated speed, and set to a value 0 in other circumstances than the above-mentioned ones.
In such a motor vehicle, during a prescribed transition from an accelerator ON state to an accelerator OFF and brake OFF state, a demand of the vehicle changes from a drive demand to a brake demand, so the vehicle is likely to become a forward tilt posture. In the above-mentioned motor vehicle, during the prescribed transition, if the rear wheel demand distribution ratio is made to directly change from a value (a value 0 or 0.2, 0.3, etc.) during the accelerator ON state to a value (0.5, 0.4, etc.) during the accelerator OFF and brake OFF state, it is possible that the vehicle becoming the forward tilt posture cannot be sufficiently suppressed.